Hydrazone compound and photosensitive material using said compound

ABSTRACT

The present invention provides a hydrazone compound represented by the following general formula (1). This compound has higher hole mobility as compared with an electric charge transferring material such as the conventional hydrazone compound or the like. Accordingly, when this compound is contained in a photosensitive layer as the electric charge transferring material, there may be obtained an electrophotosensitive material excellent in sensitivity, charging ability and repeat characteristics. ##STR1## (wherein R 1  is a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and R 2  is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or the following group.) ##STR2##

BACKGROUND OF THE INVENTION

The present invention relates to a novel hydrazone compound, and alsorelates to a photosensitive material using such a compound.

As a photosensitive material in an image forming apparatus such as anelectrophotographic copying apparatus, a printer or a facsimile, therehas recently and widely been used an organic photosensitive materialwhich is excellent in machinability and advantageous in production costand which offers a great degree of freedom for design of performance.

For forming a copied image with the use of an electrophotosensitivematerial, the Carlson process is widely used. The Carlson processcomprises the steps of uniformly charging a photosensitive material withelectricity by corona discharge, exposing the charged photosensitivematerial to a document image, thereby to form an electrostatic latentimage corresponding to the document image, developing the electrostaticlatent image by a toner containing developer, thereby to form a tonerimage, transferring the toner image to a medium such as paper, fixingthe toner image transferred to the medium, and cleaning thephotosensitive material to remove toner remaining thereon after thetoner image has been transferred. To form an image of high quality inthe Carlson process, it is required that the electrophotosensitivematerial is excellent in charging and photosensitive characteristics andpresents a low residual potential after exposed to light.

Conventionally, there have been known inorganic photoconductivematerials such as selenium, cadmium sulfide and the like aselectrophotosensitive materials. However, these inorganicphotoconductive materials are toxic and need great production costs.

There has been proposed a so-called organic electrophotosensitivematerial using various organic substances in place of theabove-mentioned inorganic substances. Such an organic photosensitivematerial has a photosensitive layer comprised of an electric chargegenerating material for generating electric charges by light exposureand an electric charge transferring material having a function oftransferring the electric charges thus generated.

To meet various requirements for the organic electrophotosensitivematerial, it is necessary to properly select the electric chargegenerating material and the electric charge transferring material. Asthe electric charge transferring material, various organic compoundshave been proposed and put on the market. By way of example, a hydrazonecompound represented by the following formula (x) serving as theelectric transferring material has been disclosed in Japanese UnexaminedPatent Publication No. 272571/1990. ##STR3## (wherein A¹ and A² are thesame as or different from each other and each is a lower alkyl group, abenzyl group or a phenyl group, or they may be bonded to each other,thereby to form a heterocycle together with adjacent nitrogen atoms.)

Referring to the electric charge transferring material according to theprior art, however, sensitivity and repeat characteristics are notsufficient.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hydrazone compoundsuitable for an electric charge transferring material.

It is another object of the present invention to provide anelectrophotosensitive material excellent in sensitivity and repeatcharacteristics.

The hydrazone compound of the present invention is represented by thefollowing general formula (1): ##STR4## (wherein R¹ is a hydrogen atom,a halogen atom, an alkyl group or an alkoxy group, and R² is a hydrogenatom, a halogen atom, an alkyl group, an alkoxy group or the followinggroup.) ##STR5##

The hydrazone compound of the present invention is effective as theelectric charge transferring material, in particular, as a holetransferring material and has higher hole mobility as compared with theelectric charge transferring material such as the hydrazone compoundaccording to the prior art, or the like which is represented by thegeneral formula (x).

A photosensitive material containing the hydrazone compound (1) isexcellent in sensitivity and charging ability and has high repeatcharacteristics.

DETAILED DESCRIPTION OF THE INVENTION

Examples of the alkyl group include a lower alkyl group having 1 to 6carbon atoms, methyl, ethyl, propyl, isopropyl, butyl, isobutyl,t-butyl, pentyl and hexyl groups.

Examples of the alkoxy group include a lower alkyl group having 1 to 6carbon atoms in its alkyl portion, methoxy, ethoxy, isopropoxy, butoxy,t-butoxy and hexyloxy groups.

Examples of the halogen atom include chlorine, iodine, bromine andfluorine.

As specific examples of the hydrazone compound represented by thegeneral formula (1), the following compounds are mentioned. ##STR6##

The compound of the general formula (1) may be composed by the followingreaction formula (see C. Mannich et al., Ber., 69, 2106, 2112 (1936)):##STR7## (wherein R¹ and R² are the same as mentioned above.)

An aldehyde compound of the formula (a) and a compound of the formula(b) are reacted in a suitable acidic solvent to which acetic acid andthe like are added, thereby to give the hydrazone compound (1) of thepresent invention. Reaction is carried out in the solvent at 10° to 25°C. Examples of the solvent include ether, tetrahydrofuran, dioxane andthe like.

The compound of the general formula (1) in accordance with the presentinvention may be contained, in a binding resin, alone or in combinationwith the other conventional electric charge transferring material,thereby to form a photosensitive layer. Examples of the conventionalelectric charge transferring material include nitrogen-containing cycliccompounds and condensed polycyclic compounds which include oxadiazolecompounds such as 2,5-di(4-methylaminophenyl)-1,3,4-oxadiazole and thelike, styryl compounds such as 9-(4-diethylaminostyryl) anthracene andthe like, carbazole compounds such as polyvinyl carbazole and the like,pyrazoline compounds such as 1-phenyl-3-(p-dimethylaminophenyl)pyrazoleand the like, triphenylamine compounds, indole compounds, oxazolecompounds, isooxazole compounds, thiazole compounds, thiadiazolecompounds, imidazole compounds, pyrazole compounds, triazole compoundsand the like. These examples of the electric charge transferringmaterial may be used alone or in combination of plural types. When thereis used the electric charge transferring material having film-formingproperties such as polyvinyl carbazole or the like, a binding resin isnot necessarily required.

The compound of the general formula (1) may be used for a photosensitivematerial of the so-called single- or multi-layer type.

To form a single-layer type photosensitive material, there may beformed, on a conductive substrate, a photosensitive layer containing thecompound of the general formula (1) serving as the electric chargetransferring material, an electric charge generating material, a bindingresin and the like.

To form a multi-layer type photosensitive material, an electric chargegenerating layer containing an electric charge generating material isformed on the conductive substrate, and the electric charge transferringlayer containing the compound of the general formula (1) serving as theelectric charge transferring material is then formed on the electriccharge generating layer. On the contrary, the electric charge generatinglayer may be formed on the electric charge transferring layer.

Examples of the electric charge generating material include-selenium,selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salt,azo compounds, disazo compounds, phthalocyanine compounds, anthanthronecompounds, indigo compounds, triphenylmethane compounds, threnecompounds, toluidine compounds, pyrazoline compounds, perylenecompounds, quinacridon compounds, pyrrolopyrrole compounds and the like,which have conventionally been used. These examples may be used alone orin combination of plural types.

As the binding resin, any of a variety of resins may be used. Examplesof the binding resin include various polymers which include:thermoplastic resins such as a styrene polymer, a styrene-butadienecopolymer, a styrene-acrylonitrile copolymer, a styrene-maleic acidcopolymer, an acrylic copolymer, a styrene-acrylic acid copolymer,polyethylene, an ethylene vinyl acetate copolymer, chlorinatedpolyethylene, polyvinyl chloride, polypropylene, a vinyl chloridevinylacetate copolymer, polyester, alkyd resin, polyamide, polyurethane,polycarbonate, polyarylate, polysulfon, dialyl phthalate resin, ketoneresin, polyvinyl butyral resin, polyether resin and the like,crosslinking thermosetting resins such as silicone resin, epoxy resinand the like; photosetting resins such as epoxy-acrylate,urethane-acrylate and the like. These polymers may be used alone or incombination of plural types.

Examples of a solvent for dissolving the electric charge generatingmaterial, the electric charge transferring material and the bindingresin to prepare a coating solution include: alcohols such as methanol,ethanol, isopropanol, butanol and the like; aliphatic hydrocarbons suchas n-hexane, octane, cyclohexane and the like; aromatic hydrocarbonssuch as benzene, toluene, xylene and the like; halogenated hydrocarbonssuch as dichloromethane, dichloroethane, carbon tetrachloride,chlorobenzene and the like; ethers such as dimethyl ether, diethylether, tetrahydrofuran, ethylene glycol dimethyl ether, diethyleneglycol dimethyl ether and the like; ketones such as acetone, methylethylketone, cyclohexanone and the like; esters such as ethyl acetate, methylacetate and the like; dimethylformaldehyde; dimethylformamide;dimethylsulfoxide and the like. These solvents may be used alone or incombination of plural types.

To improve the electric charge generating layer in sensitivity, theremay be used a conventional sensitizer such as tert-phenyl,halonaphtoquinone, acenaphthylene or the like, together with theelectric charge generating material.

To improve the electric charge transferring and generating materials indispersibility, aplicability and the like, there may be used asurfactant, a levelling agent and the like.

Examples of the conductive substrate include: single metal such asaluminium, copper, tin, platinum, silver, vanadium, molybdenum,chromium, cadmium, titanium, nickel, paradium, indium, stainless copper,brass and the like; plastic material vapor-deposited or laminated withany of the metals above-mentioned; glass material coated with aluminiumiodide, tin oxide, indium oxide or the like.

The conductive substrate may be made in the form of a sheet or a drum.The substrate itself may be conductive or only the surface of thesubstrate may be conductive. Preferably, the substrate has a sufficientmechanical strength when used.

In the multi-layer type photosensitive material, the electric chargegenerating material forming the electric charge generating layer and thebinding resin may be used at a variety of ratios. Preferably 5 to 500parts by weight and more preferably 10 to 250 parts by weight of theelectric charge generating material may be used for 100 parts by weightof the binding resin.

The thickness of the electric charge generating layer is optional, butis preferably from 0.01 to 5 μm and more preferably from 0.1 to 3 μm.

The compound (electric charge transferring material) of the generalformula (1) forming an electric charge transferring layer and thebinding resin may be used at a variety of ratios. Preferably 10 to 500parts by weight and more preferably 25 to 200 parts by weight of thecompound of the general formula (1) may be used for 100 parts by weightof the binding resin such that electric charges generated on theelectric charge generating layer can easily be transferred by lightradiation.

The thickness of the electric charge transferring layer is preferablyfrom 2 to 100 μm and more preferably from 5 to 30 μm.

In the single-layer type photosensitive material, preferably 2 to 20parts by weight and more preferably 3 to 15 parts by weight of theelectric charge generating material, and preferably 40 to 200 parts byweight and more preferably 50 to 150 parts by weight of the compound ofthe general formula (1) (electric charge transferring material) may beused for 100 parts by weight of the binding resin. The thickness of thesingle-layer type photosensitive layer is preferably from 10 to 50 μmand more preferably from 15 to 30 μm.

When the photosensitive layer including the electric charge generatinglayer and the electric charge transferring layer is formed with coatingmeans, the electric charge generating material or electric chargetransferring material and the binding resin may be dispersed and mixedwith the use of any of conventional methods, for example, a roll mill, aball mill, an atriter, a paint shaker, a supersonic dispenser or thelike, then to prepare a coating solution.

EXAMPLES

The following description will discuss in detail the present inventionwith reference to examples and comparative examples thereof.

(1) Synthesis Examples of Electric Charge Transferring Material Example1 Synthesis of a compound represented by the formula (12)

3.63 g Of an aldehyde compound of the following formula (23) and 1.84 gof diphenyl hydrazine (C₆ H₅)₂ were agitated and reacted at a roomtemperature in an acidic solvent (60 ml) to which acetic acid is added,thereby to prepare a compound of the formula (12). ##STR8##

This compound had a melting point of 195° to 198° C. The following showsthe results of elemental analysis.

In C₃₈ H₃₁ N₃ : Calculation Values--C:86.17%, H:5.90%, N:7.93%. MeasuredValues--C:86.09%, H:5.85%, N:7.89%.

Each compound was prepared by using suitable starting materials in thesame manner as in Example 1. The compounds thus obtained are as follows.

Example 2 Compound of the formula (11)

This compound had a melting point of 188° to 190° C. The following showsthe results of elemental analysis.

In C₃₇ H₂₉ N₃ : Calculation Values--C:86.18%, H:5.67%, N:8.15%. MeasuredValues--C:86.01%, H:5.70%, N:8.11%.

Example 3 Compound of the formula (13)

This compound had a melting point of 235° to 237° C. The following showsthe results of elemental analysis.

In C₅₀ H₃₉ N₅ : Calculation Values--C:84.59%, H:5.54%, N:9.87%. MeasuredValues--C:84.50%, H:5.51%, N:9.89%.

(2) Preparation of Electrophotosensitive Material Preparation ofMulti-Layer Type Electrophotosensitive Material Examples 4 to 6 andComparative Examples 1 and 2

2 Parts by weight of the electric charge generating material of thefollowing formula (A), 1 part by weight of a polyvinyl butyral resin("S-lecBH-5" manufactured by Sekisui Kagaku Kogyo Co., Ltd.) and 120parts by weight of tetrahydrofuran were dispersed for 2 hours by meansof a paint shaker using zirconia beads (having a diameter of 2 mm). Thedispersing solution thus prepared was applied, by means of a wire bar,to an aluminium sheet, which was then dried at 100° C. for 1 hour. Thus,an electric charge generating layer with a thickness of 0.5/ μm wasformed. ##STR9##

1 Part by weight of the electric charge transferring material and 1 partby weight of a polycarbonate resin ("Z-200" manufactured by MitsubishiGas Kagaku Kogyo Co., Ltd.) were dissolved in 9 parts by weight oftoluene. The solution thus prepared is applied, by means of the wirebar, to the electric charge generating layer, which was then dried at100° C. for 1 hour. Thus, an electric charge transferring layer with athickness of 22 μm was formed. The electric charge transferringmaterials used in Examples 4 to 6 are indicated at compound numbersshown in the above-mentioned specific examples in Table 1. The electriccharge transferring materials (24) and (25) used in Comparative Examples1 and 2 are compounds represented by the following formulas (24) and(25) in Table 1. ##STR10##

Preparation of Single-Layer Type Electrophotosensitive Material Examples7 to 9 and Comparative Examples 3 and 4

1 Part by weight of the electric charge generating material of theformula (A) and 60 parts by weight of tetrahydrofuran were dispersed for2 hours by means of a paint shaker using zirconia beads (having adiameter of 2 mm). To the dispersing solution thus prepared are added 50parts by weight of a tetrahydrofuran solution of a polycarbonate resinhaving 20 % by weight of a solid content ("Z-200" manufactured byMitsubishi Gas Kagaku Kogyo Co., Ltd.) and 10 parts by weight of theelectric charge transferring material, which were further dispersed for1 hour. The dispersing solution thus prepared was applied, by means of awire bar, to an aluminium sheet, which was then dried at 100° C. for 1hour. Thus, a photosensitive layer with a thickness of 20 μm was formed.The electric charge transferring materials used in Examples 7 to 9 andComparative Examples 3 and 4 were indicated at respective compoundnumbers in the same manner as in the above-mentioned Examples shown inTable 1.

(3) Evaluation of the Electrophotosensitive Material

The surface potential, half-life light exposure (E_(1/2)) and residualpotential of the photosensitive material obtained in the above-mentionedExamples and Comparative Examples were measured by means of anevaluation tester ("EPA8100" manufactured by Kawaguchi Denki Co., Ltd.).

Measuring conditions are as follows.

Light Intensity: 50 lux

Exposure Intensity: 1/15 second

Surface Potential: A flowing current value was adjusted so as toapproximate (±)700 V.

Light Source: Tungsten lamp

Electric Removal: 200 lux

Measurement of Residual Potential: Measurement was started afterexposure continued for 0.2 second.

The test results of the Examples 4 to 6 and Comparative Examples 1 and2, and those of the Examples 7 to 9 and Comparative Examples 3 and 4 areshown in Tables 1 and 2, respectively.

                  TABLE 1    ______________________________________    Electric charge Surface            Residual    transferring    potential                             E.sub.1/2 potential    material        (V)      (lux · sec)                                       (V)    ______________________________________    Example 12          -701     1.23    -122      4    Example 11          -704     1.20    -120      5    Example 13          -700     1.01    -108      6    Compar- 24          -702     1.88    -150    ative    Example      1    Compar- 25          -710     1.55    -139    ative    Example      2    ______________________________________

                  TABLE 2    ______________________________________    Electric charge Surface            Residual    transferring    potential                             E.sub.1/2 potential    material        (V)      (lux · sec)                                       (V)    ______________________________________    Example 11          +705     2.51    +155      7    Example 12          +702     2.58    +158      8    Example 13          +698     2.35    +140      9    Compar- 24          +700     3.00    +180    ative    Example      3    Compar- 25          +701     2.80    +168    ative    Example      4    ______________________________________

As seen from these test results, the photosensitive layer of each ofExamples has almost the same surface potential as in ComparativeExamples, but is more excellent in half-life light exposure and residualpotential and has its sensitivity remarkably improved.

What is claimed is:
 1. A photosensitive material comprising:a conductivesubstrate; a photosensitive layer on the conductive substrate, whichphotosensitive layer contains a hydrazone compound as an electric chargetransferring material, wherein the hydrazone compound is represented bythe following formula: ##STR11## wherein R¹ is a hydrogen atom, ahalogen atom, an alkyl group or an alkoxy group, and R² is a hydrogenatom, a halogen atom, an alkyl group, an alkoxy group or the followinggroup: ##STR12##
 2. The photosensitive material according to claim 1,wherein the photosensitive layer is a multi-layer type photosensitivelayer including an electric charge transferring layer which includes thehydrazone compound as the electric charge transferring material, and anelectric charge generating layer, which layers are laminated mutually.3. The photosensitive material according to claim 2, wherein theelectric charge transferring layer of the multi-layer typephotosensitive layer further includes a binding resin, and the electriccharge transferring layer contains 25 to 200 parts by weight of saidhydrazone compound for 100 parts by weight of the binding resin.
 4. Thephotosensitive material according to claim 3, wherein the electriccharge generating layer further includes a binding resin for theelectric charge generating layer, wherein the electric charge generatinglayer contains, for 100 parts of the binding resin for the electriccharge generating layer, 5 to 500 parts by weight of one or more kindsof an electric charge generating material selected from selenium,selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salt,azo compounds, disazo compounds, phthalocyanine compounds, anthanthronecompounds, indigo compounds, triphenylmethane compounds, threnecompounds, toluidine compounds, pyrazoline compounds, perylenecompounds, quinacridon compounds, and pyrrolopyrrole compounds.
 5. Thephotosensitive material according to claim 4, wherein the electriccharge generating material is an azo compound.
 6. The photosensitivematerial according to claim 1, wherein the photosensitive layer is asingle-layer type photosensitive layer comprised of an electric chargetransferring material, an electric charge generating material and abinding resin.
 7. The photosensitive material according to claim 6,wherein the single-layer type photosensitive layer contains 40 to 200parts by weight of said hydrazone compound for 100 parts by weight ofthe binding resin.
 8. The photosensitive material according to claim 7,wherein the single-layer type photosensitive layer contains, for 100parts by weight of the binding resin, 2 to 20 parts by weight of one ormore kinds of an electric charge generating material selected fromselenium, selenium-tellurium, selenium-arsenic, amorphous silicon,pyrylium salt, azo compounds, disazo compounds, phthalocyaninecompounds, anthanthrone compounds, indigo compounds, triphenylmethanecompounds, threne compounds, toluidine compounds, pyrazoline compounds,perylene compounds, quinacridon compounds, and pyrrolopyrrole compounds.9. The photosensitive material according to claim 8, wherein theelectric charge generating material is an azo compound.